Open-side compression tool



Aug. 23, 1966 w. REISCHER OPEN-SIDE COMPRESSION TOOL 2 Sheets-Sheet 1 Filed Jan. IO, 1964 Aug. 23, 1966 w. REISCHER OPEN-SIDE COMPRESSION TOOL 2 .Sheets-Sheet 2 Filed Jan. lO, 1964 United States Patent O 3,267,717 OPEN-SlDE CGMPRESSION TL Walter Reisciler, Darien, Conn., assignor to Burndy Corporation, a corporation of New York Filed `Ian. 10, 1964, Ser. No. 337,033 8 Claims. (Cl. 72-416) This invention relates to an open-side operating head for a compression tool, commonly referred to as a C- head. Such operating heads are employed in uid powered (hydraulic and pneumatic, for example) tools which are used for a Wide variety of purposes, such as crimping of electrical connectors, where it is not possible or convenient to .axially remove the work piece fro-rn the tool. The opposed force applying jaws of these operating heads are commonly provided with a pair of removable crimping dies which may be interchanged to accommodate work pieces of varying size. Due to the magnitude and nature of the stresses developed in use, C-shaped or open-side operating heads are generally of massive construction in order to provide the necessary support for the dies and sufficient rigidity to prevent deflection and consequent die misalignment; they are therefore usually extremely heavy.

It is an object of the present invention to provide a C-head for a compression tool which is lighter in weight than conventional heads of equal capacity and yet suffers no increase in structural deflection and die mis-alignment under equivalent compression force.

Conversely, it is object of this invention to increase the allowable maximum force which may be generated in a C-head of given bulk and weight while limiting structural deflection and die misalignment to values equal to or less than those encountered in existing tools of similar size.

A still further object is to provide the foregoing advantages in a construction which is applicable to both mechanical and hydraulic compression tools.

These and other objects are obtained and new results accomplished by this invention as will become apparent from consideration of the C-heads which are hereinafter described, particularly pointed out in the appended claims, and illustrated in the accompanying drawings in which:

FIGURE l is a cross sectional view of a hydraulic tool compression head incorporating this invention;

FIGURE 2 is a partially sectioned top view of the C- head of FIGURE l; and

FIGURE 3 is a side section View of another embodiment of this invention.

In ybroad concept, the C-head of this invention is provided with means for providing a balancing 'force which is in opposition to the forces ygenerated by the jaws of the head in compressing work piece. By balancing rather than rigidly resisting .the bending force generated during use, it is possible to substantially reduce the mass of the tool below that of the rigid resisting structures commonly employed. The balancing forces may be made equal in effect to the forces generated by closing of the compressing jaws and may be varied in proportion to the load, as shown by the construction illustrated in FIGURE l; alternatively, the balancing forces may be selected to obtain ya specific predetermined value suflicient to counterbalance the forces likely to Abe encounteredin a specific application.

Referring now more particularly to the drawings, the variable balancing force compression head of FIGURE l may be seen to comprise a lower body portion and an upper opposed body portion 12 which are joined together by one or more axial tension bolts 14. -In the ernlbodiment shown, the upper and lower body portions are spaced apart by a pair of tubular spacers such as 16,

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which are coaxial with the tension :bolts intermediate the two 'body portions. Other spacing means may obviously be used in connection with the bolts in place of the tubular spacers; these latter provide the advantages of low weight, low cost and simplicity of assemlbly.

A pair of cylindrical bores 18 and Z0 `are formed in lower body portion 10 for cooperatively receiving compression force applying ram 22 and balancing force applying ram 24, respectively. Pressure fluid inlet 26 is operatively connected to fluid passages 28 and 30 for applying fluid pressure to the force applying rams within the two bores 18 and 20. Each of the rams 22 and 24 may be provided with a piston ring 32 and 34 respectively to seal the ram to the bore wall.

The upper part of ram 22 is provided with :a seat 36 for receiving one half-section 38 of compressing die. The opposed part of upper body portion 12 similarly includes a seat `40 for removably receiving a mating die half-section 42. As fluid pressure is applied to ram 22 the ram advances axially toward the upper body portion "12 to compress an electrical connection such as 44 (shown in dot dash lines) between the substantially channel-shaped die surfaces 46 and 48, in a well known manner.

To prevent rotation of the ram 22 about its own axis to thereby assure maintenance of the parallel relationship between the axes of the two die-half-sections, the die-receiving upper portion of the ram includes a puojection 48 which extends between the spacers 16 on the -bolts 14 as shown in FIGURE 2. The opposed trans-A verse edges `50 of the projection 48 form a pair of bearing surfaces (only one being shown in FIGURE 2) which engage the spacers or col-lars 16 in sliding relationship to permit longitudinal movement of the ram .While preventing axial rot-ation.

As a connector is compressed between the jaws by the application of fluid pressure to the base of ram 22, the force transmitted through the connector to upper body portion 12 tends to tilt the body portion relative to the plane defined by the axes of the bolts 14. However, the fluid pressure applied to ram 22 is simultaneously applied to balancing ram 24 which produces an opposing f-orce tending to tilt the body portion 12y in the opposite direction. The bolt axes thus dene a neutral plane through the body portion 12, with bending-'moment deformation of the body portion occurring to the left and right of the plane.

In a side-opening operating head of the commonly known type having aunitary structure, the portion of the head corresponding to the area rbetween the axes of the bolts 14 and the axis of the balancing r-am 24 might be formed `of a solid mass of material integral with the upper and lower body portions 10 and 12. The neutral axis of such a structure would be substantially to the left of the effective neutral axis 'of this invention, the indio cated mass of material would be in tension to the right of the neutral axis and in compression to the left, and the resultant total reflection of the upper die section relative to the lower die section would correspondingly be substantially greater than in the compression headl of this invention.

It should be noted that in the present invention any elongation of the tension bolts 14 during operation which tends to permit upper body portion 12 to tilt relative thereto as a result of the force applied in compressing the connector, is fully compensated by the corresponding displacement of the body along the axis of the balancing force applying ram.

The factors involved in determining the desirable design dimensions of an operating head constructed in accordance with this invention are in essence, the pressure applied by each of the force applying rams as a result of a given huid pressure, vand the distance from the centra] axis of each of the rams to the effective neutral plane. Thus, if A22 and A24 are assumed to represent the areas respectively of the rams 22 and 24, and D22 and D24 are assumed to represent the respective distances between the aXis of eachram and the plane dened by the tension bolts 14, then for a given iluid pressure, bending moment balance w-ill be achieved if the simple relationship A22 D22=A24 D24 is satisiied.

In the modified version of this invention illustrated in FIGURE 3, the operating head comprises a lower body portion110 and an upper body portion 112 which are joined together by tension bolt v11d, and spaced apart by a spacing collar 116. Body portion 11G is provided with a cylindrical bore 118 having a compression torce applying ram 122 itted therein; and both the ram and the upper body portion 112 are litted with complementary die halt sections 132 and 134 respectively. Compression forces are transmitted to any connector disposed between the die half sections 132 and 134i by means of fluid pressure applied through` fluid inlet passage 126, to ram 122 in the Well-known manner described with reference to the ernbodiment of FIGURES l and 2. 'I-'he balancing ram arrangement of the embodiment of FIGURE l uses tubular element merely to space body portions 1t) and 12; in'the present embodiment, body 112 is pro-vided with a balancing force receiving pad 160 which rests upon the surface of a corresponding oiset portion 162 of the lower body portion 110, and the tension bolt 114 is preloaded, by tightening tension bolt nut 150 beyond the force necessary merely to secure the upper and lower body portions together, in order to seat pad 160 securely on portion 162. The initial deflection of the entire head assembly due to preloading of the bolt is then relieved during compressio-n of a connector to thereby limit the maximum total detiection caused by compression. lower total deflection is .achieved by this method than would occur in the absence of preloading. The deection stresses generated in this embodiment, during application of maximum compression force, are balanced :by ram 12d in substantially the same manner as those generated in the corresponding portions of the embodiment of FIG- URE 1. The portions of the embodiment of FIGURE 3 which correspond to like portions ot FIGURE 1 are denoted by identical numbering transposed to the "ls series.

The advantages of the two embodiments herein described, over conventional rigid C-shapedoperating heads, include reduced volume and weight of material employed, feasibility of selecting optimum deflection-resisting configurations for the various parts; and, more accurate maintenance of alignment between the die sections during compression operation. It should be noted that the forces developed in the retaining bolts of both embodiments are tension forces only, Iand these may be easily handled by adequately designed bolts formed of -any one ot many well known materials. The head assemblies of this invention may nevertheless be designed with the bolts as the weakest link, so that, upon failure or permanent deformation, substantial savings may be eiected by salvaging the principal and most costly parts of the operating head through simple replacement of the bolts. It is thus clear that even the entire upper body portion, including the connecting bolt or bolts, may be replaced without loss of the costly cylinder bore and fluid passage bearing portion, as would be necessary in unitary operating heads of conventional design.

It should be understood that the force applied to the died parts may be developed bymeans others than the uid power mechanisms selected for illustration in the drawings. The force may be derived for example, from electric motors or from manually operated linkages employing well known techniques for obtaining the necessary mechanical advantage and for moving one die section relative to the other.

The invention has thus been described but itis desired to be understood that it is not confined to the particular forms or usages shown and described, the same being merely illustrative, and that the invention may be carried out in other ways Without departing from the spirit of the int vention; therefore, the righ-t is broadly claimed to employ all equivalent instrumentalities com-ing within the scope of the appendent claims, and by means of which objects of this invention are attained and new results accomp-` lished, as it is obvious that the particular embodiments herein shown and described are only some of the many that can be employed to obtain these objects and accomplish these results.

I claim:`

1. An operating head fora compression tool, comt prising: a rst body portion supporting a die section, a second body portion supporting a complementary die section; means tor holding the first body portion to the second body portion; means on one side of said holding means for advancing one die section toward the other die section independently of said body portions; and means for applying ya counterbalancing force, on substantially the opposite side of said holding means, to resist tilting of the two body portions with respect to each other.

2. The operating head of claim 1 wherein said holding means includes a tension bolt disposed intermediate said advancing means and said countenbalancing means.

3. The operating head of claim 1, wherein said die section advancing means includes a fluid pressure `actuated ram, and said counterbalancing force applying means includes another iiuid pressure actuated ram.

d. The operating head of claim 3, wherein said rams are operated by a common source of iluid pressure such that the force applied by said counterbalancing ram Varies directly as the value of the force applied by said advancing means.

5. The operating head of claim 3, wherein the perpendicular distance between the axes of said `advancing means ram and said holding means, multiplied by the instantaneous force applied by said advancing means ram, is equal to the perpendicular distance between the axis of said counterbalancing ram and said holding means, multiplied by the force applied by said counterbalancing ram at the corresponding time during compression.

6. The operating head of claim 3 wherein said holding means includes at least a tension bolt disposed intermediate said advancing means ram and said counterbalancing means ram, and said advancing means ram includes means engaging said bolt for preventing rotation of said advancing ram.

,'7. The operating head of claim 1, wherein said holding means includes a pair of parallel spaced-apart tension bolts disposed intermediate said counterbalancing force applying means and said advancing means, said bolts being disposed in a plane which is substantially perpendicular to the plane defined by the axes of said force applying and advancing means.

S. The operating head of claim 7 wherein: said counterbalancing force means includes a portion of said rst body portion directly engaging an opposed portion of said second body portion; and, said tension bolt is pretightened to hold said engaging body portions together with a force substantially equal to the maximum force applied by said die section advancing means duringr compression.

References Cited by the Examiner UNITED STATES PATENTS l/l959 Swanson 72-453 l/l962 lKlein 72--416 

1. AN OPERATING HEAD FOR A COMPRESSION TOOL, COMPRISING: A FIRST BODY PORTION SUPPORTING A DIE SECTION, A SECOND BODY PORTION SUPPORTING A COMPLEMENTARY DIE SECTION; MEANS FOR HOLDING THE FIRST BODY PORTION TO THE SECOND BODY PORTION; MEANS ON ONE SIDE OF SAID HOLDING MEANS FOR ADVANCING ONE DIE SECTION TOWEARD THE OTHER DIE SECTION INDEPENDENTLY OF SAID BODY PORTIONS; AND MEANS FOR APPLYING A COUNTERBALANCING FORCE, ON SUBSTANTIALLY THE OPPOSITE SIDE OF SAID HOLDING MEANS, TO RESIST TILTING OF THE TWO BODY PORTIONS WITH RESPECT TO EACH OTHER. 